No satisfactory synthetic substitute is available for human vein for myocardial revascularization procedures, although there are isolated reports of success using several different synthetic arterial prostheses. A new synthetic material, IMPRAR, an expanded polytetrafluorethylene compound has been recently modified to enhance antithrombogenicity by impregnating the inner aspect of the graft with particulate graphite. This study is designed to evaluate this new material as a possible substitute for vein in revascularization of myocardium. Ten adult foxhounds underwent left thoracotomy and cardiopulmonary bypass, with subsequent cardiac arrest sustained with cold crystalloid potassium cardioplegia. A short segment of tapered graphite impregnated Impra was imposed as a bypass segment to the LAD coronary artery distal to a ligature placed to occlude that vessel. Six dogs survived and underwent catheterization and coronary angiography between the 30th and 60th postoperative day. All grafts were occluded and in no animal could the native vessel be visualized by retrograde flow.